The term Jacob's staff, also cross-staff, a ballastella, a fore-staff, or a balestilha, is used to refer to several things. This can lead to considerable confusion unless one clarifies the purpose for the object so named. The two most frequent uses are:
- in astronomy and navigation for a simple device to measure angles, later replaced by the more precise sextants;
- in surveying for a vertical rod that penetrates the ground and supports a compass or other instrument.
Read more about Jacob's Staff: Astronomy and Navigation, Surveying
Famous quotes containing the words jacob and/or staff:
“As for me, Abraham, Isaac, and Jacob are now only the subtlest imaginable essences, which would not stain the morning sky.”
—Henry David Thoreau (1817–1862)
“... all my letters are read. I like that. I usually put something in there that I would like the staff to see. If some of the staff are lazy and choose not to read the mail, I usually write on the envelope “Legal Mail.” This way it will surely be read. It’s important that we educate everybody as we go along.”
—Jean Gump, U.S. pacifist. As quoted in The Great Divide, book 2, section 10, by Studs Terkel (1988)